The person testing overdue fines at renewal noticed that for item 11486494, overdue fines were not generated when the item was overdue then renewed. The Overdue Fine Policy had setting "Forgive overdue fine if item renewed" set to "No". This means that the item should have been billed an overdue fine.
Holly then looked at the inventory record for 11486494 and discovered that the Location area looks like this...
The overdue calculation must be using one of the location fields that is blank to determine the Fee/Fine Owner of the overdue fine. It never occurred to Holly that an item being circulated wouldn't at least have a Permanent Location. Luckily this issue was solved for us when the "Effective location for item" field was created. We should change the overdue process to use this value of "Effective location for item" when determine who the Fee/Fine Owner is.